EFFECTS OF CATTLE GRAZING ON SMALL MAMMAL COMMUNITIES AT RED ROCK LAKES NATIONAL WILDLIFE REFUGE, MONTANA

Abstract

Cattle grazing is a common land-use on public land in the Intermountain West that often has varied and complex effects on wildlife. We undertook the current study to better understand the response of small mammals to the frequency of cattle grazing in wet meadow habitats on Red Rock Lakes National Wildlife Refuge. Three adjacent grazing units were selected for study that provided a range of rested grazing units (one, three, and eight years of rest). We captured and marked 363 individuals, and had 174 recaptures on six 1.8 ha grids over 27 days. Voles (Microtus spp.) comprised 99 percent of individuals captured, with two deer mice (Peromyscus maniculatus), and one common shrew (Sorex cinereus). Vole abundance increased with increasing rest from grazing. Nearly 61 percent (221) of voles were captured in the unit with 8 years of rest from grazing; 26 percent (94) and 13 percent (48) of total captures were in units of three and one year of rest, respectively.  Apparent 8 day survival probability estimates were 0.45 (±0.12 SE), 0.62 (±0.12) and 0.35 (±0.09) for treatments with one, three and eight years of rest, respectively. Litter depth and physiognomic classes litter, and forb, and bare ground approached an asymptote after three years rest from grazing.